As an IC label used for RFID, there are conventionally known identification IC labels consisting of an electrically connected antenna coil and an IC chip on which information is stored.
When these IC labels receive electromagnetic waves from a reader/writer, electromotive force is generated in the antenna coil by a resonance action, the IC chip in the IC label is activated by the electromotive force, information in the chip is converted to a signal, and this signal is transmitted from the antenna coil of the IC label.
The signal sent from the IC label is received by the antenna of the reader/writer and sent to a data processing device through a controller, where data processing such as identification is performed.
In order for these IC labels to operate, the electromagnetic waves transmitted from the reader/writer must be sufficiently picked up by antenna coil of the IC label and electromotive force not below the operational electromotive force of the IC chip must be induced. However, when IC labels are attached to the surfaces of metal articles, on the surface of metal articles, the flux becomes parallel to the surface of the metal articles. Because of this, the problem arises of the flux that crosses the antenna coil of the IC label decreasing, causing the induced electromotive force to drop below the actuation electromotive force of the IC chip, so that the IC chip does not operate (for example, refer to nonpatent document 1).
FIG. 4 is a mimetic diagram showing the flow of flux in the case of an IC label placed on the surface of a metal article. Since the flux 142 generated from the reader/writer 141 becomes parallel to the surface of the metal article 143 , the flux that passes the antenna coil 145 of the IC label 144 installed on the surface of the metal object article 143 decreases, and since the electromotive force induced by the antenna coil 145 declines, the IC chip 146 stops operating.
In order to enable operation even when installed on a metal article, a method has been proposed to increase the induced electromotive force by winding an antenna coil around a ferrite core, arranging the antenna coil so that its axial center may become parallel to the direction of the flux of the surface of the metal article, and increasing the flux which passes through an antenna coil surface to increase the induced electromotive force (for example, refer to patent document 1).
FIG. 5 is a perspective view of the IC tag according to the embodiment of patent document 1, showing an antenna coil 152 wrapped around the perimeter of a square-shaped ferrite core 156, and at the portion where the antenna coil 152 is not wrapped, an IC chip 153 and a condenser 154 are mounted on the substrate 155 via the substrate 155. If the flat portion of the square-shaped ferrite core 156 (underside of FIG. 5) is attached to the surface of a metal article, flux parallel to the surface of the metal article passes through the ferrite core 156. Since it passes perpendicular to the antenna coil 152, the necessary induced voltage occurs and the IC chip 153 operates.
On the other hand, it has also been proposed that by forming a flat antenna coil and causing flux to pass a magnetic core member provided on the underside of the antenna coil, the flux is made to pass through the flat antenna coil to generate induced electromagnetic force in the magnetic core member, and by providing a conductive member on the underside of the antenna coil, the impact of the article on which the IC label is to be installed on the IC label is inhibited (for example, refer to patent document 2).
FIG. 6 is a sectional drawing showing the embodiment of the invention disclosed in patent document 2. The antenna coil 161 for IC labels consists of a conductor 161a spirally wound within a flat surface, and is equipped with a plate-like or sheet-like magnetic core member 163 glued to one side of the antenna coil 161 and a conductive member 164 on the underside of the magnetic core member 163. The magnetic core member 163 traverses a portion of the antenna coil 161 on the other surface of the substrate on which the antenna coil 161 is provided, being laminated so that one end portion goes outside of the antenna coil 161, and the other end portion comes to the center portion (inside) 162 of the antenna coil 161.
By laminating the magnetic core member 163 in this way, flux enters one end portion of the magnetic core member 163 and leaves from the other end portion, so that the flux that left the other end portion passes through the inside of the antenna coil 161 and induced electromotive force occurs in the antenna coil 161 formed by the conductor 161a. 
For this reason, even if the IC label is attached to the surface of an article 165 and the flux direction around the IC label becomes parallel with the surface of the antenna coil 161, the flux passes through the inside of the antenna coil 161. Since sufficient voltage to operate an IC chip is induced by this, the IC chip reliably operates.
Furthermore, in this embodiment, since the conductive member 164 is laminated and bonded so as cover the magnetic core member 163 on the other surface of the substrate on which the antenna coil 161 was formed, the conductive member 164 screens the passage of electromagnetic waves to an article. Therefore, irrespective of whether or not the article 165 is metal, the antenna coil 161 becomes less affected by it, and even if the surface of the article 165 is formed with metal, losses due to eddy currents produced in the metal surface do not develop, and so the RFID tag reliably functions even if attached to the metal article 165.
However, in the method disclosed in patent document 1, enlarging the diameter of the antenna coil 152 in order to increase the flux that passes the antenna coil 152 in order to increase the induced electromotive force gives rise to the problem of increasing the thickness of the IC label.
On the other hand, in the method disclosed in patent document 2, the problem arises of increased thickness of the IC label due to providing a magnetic core member and a conductive member on one surface of the substrate.
In recent years there has been use of RFID media such as non-contact IC tags, non-contact IC labels and non-contact IC cards that enable writing and reading of information in a non-contact state for information control, payments and control of merchandise and the like. These RFID media are quickly becoming popular since they enable writing and reading of information in a non-contact state and, depending on the specifications, can perform writing and reading of information simultaneously to a plurality of RFID media.
FIGS. 17A and 17B are schematic diagrams showing an example of a conventional non-contact IC tag, with FIG. 17A being a plan view showing the internal structure, and FIG. 17B being a sectional drawing along line C-C in FIG. 17A.
The non-contact IC tag 2100 of this example includes an inlet 2110 in which an antenna 2102 is formed on a resin sheet 2101 and an IC chip 2103 is mounted, and a surface sheet 2112 glued to the top of the inlet 2110 with an adhesive 2111.
An antenna 2102 is formed on the resin sheet 2101 in a coiled form, both ends thereof being connected to the IC chip 2103 by the contacts 2104. Moreover, writing and read-out of information in a non-contact state are possible for the IC chip 2103 through the antenna 2102. Moreover, the surface sheet 2112 consists of a resin film and protects the IC chip 2103 by being glued to the side of the inlet 2110 in which the IC chip 2103 is mounted.
When an information writing/reading device (not shown) provided externally is brought near the non-contact IC tag 2100, a current flows into the antenna 2102 by the electromagnetic induction from the information writing/reading device, and this current is supplied from the antenna 2102 to the IC chip 2103 via the contacts 2104. Thereby, in a non-contact state, information is written from the information writing/reading device to the IC chip 2103, and information written on the IC chip 2103 is read by the information writing/reading device.
Here, as with the non-contact IC tag 2100, in the semiconductor substrate in which an IC chip is mounted on a base substrate, the IC chip is protected by gluing a protecting member such as a surface sheet to the surface on which the IC chip is mounted.
Moreover, in a semiconductor substrate on which an IC chip is mounted, technology has been devised in which the surface on which the IC chip is not mounted is covered with a resin, and then the surface of the semiconductor substrate on which the IC chip is mounted is covered with a resin, thereby protecting the IC chip (for example, refer to patent document 3). In this technique, in a semiconductor substrate on which an IC chip is mounted, the surface on which the IC chip is not mounted is first covered with a resin. Then, a metal mold is provided on top of the semiconductor substrate, and by injecting resin into this metal mold, the surface of the semiconductor substrate on which the IC chip is mounted is covered by the resin. Thereby, the semiconductor substrate on which the IC chip is mounted becomes sealed by the resin so that, compared to a protecting member such as a surface sheet being glued to the top of the semiconductor substrate protection of the IC chip can be reinforced.
Moreover, technology has also been conceived to manufacture RFID tags by fixing to a metal mold a substrate on whose base substrate an antenna is wound and an IC chip is mounted and injecting resin into the metal mold, whereby the substrate on whose base substrate the antenna is wound and the IC chip is mounted is sealed (for example, refer to patent document 4). Compared to a protecting member such as a surface sheet being glued to the top of the semiconductor substrate, this technology can reinforce protection of the IC chip.
However, in protecting the IC chip by supplying resin onto a semiconductor substrate on whose base substrate the IC chip is mounted and sealing the semiconductor substrate with the resin as described above, at the juncture when resin is supplied on the semiconductor substrate, the IC chip may be damaged and the connections between the wiring formed on the base substrate and the IC chip may break from the pressure and heat of the resin supply.
In addition, in a semiconductor device whose semiconductor substrate, on whose base substrate an IC chip is mounted, is sealed with resin, the IC chip may be damaged and the connections between the wiring formed on the base substrate and the IC chip may break from pressure being applied to the IC chip due to expansion of the resin from changes in the surrounding environment after manufacture, particularly a rise in the ambient temperature.
In addition, when affixing an IC label on a metal container and the like, since repeated reaffixing is possible any number of times, a method of using ferromagnetic materials (such as a magnet) having spontaneous magnetization characteristics instead of an adhesive has been devised.
However, since the magnetic moment of the ferromagnetic material having spontaneous magnetization characteristics is strong, there is strong magnetic isotropy in this ferromagnetic material. Accordingly, in the IC label in which a magnetic layer consisting of a ferromagnetic material is provided so as to be in contact with the antenna, when picking up flux emitted from the information writing reading device, variations arise in the degree of flux capture, giving rise to the problem of a drop in the reading rate and reading distance.
When the thickness of the IC label increases, there is a problem of the flexibility of the IC label being impaired. When the flexibility of the IC label is impaired, it is difficult to affix the IC label on an article having a curved surface. In addition, when affixing the IC label to an article or separating it from an article, immoderate force is applied to the IC label, giving rise to the possibility of damaging the antenna or the IC chip.
Non-contact data reception/transmission units such as an IC label are used for such purposes as goods tracking.
In particular, if non-contact data reception/transmission units are applied to tracking of goods of many types and machine parts with many components, since the good itself can be identified without viewing, the efficiency of such operations as selection of an item and inventory control can be raised, and so it is extremely effective.
In the case of using a non-contact data reception/transmission unit for tracking of a good, it is directly affixed to the good to be tracked. Therefore, depending on the use of an article, the non-contact data reception/transmission unit may be damaged by an external impact, causing its communication facility to be impaired. Therefore, a non-contact data reception/transmission unit has been proposed with a structure able to withstand external impacts by providing a protective construction such as housing the inlet in a case, or covering it with resin.
As methods of manufacturing the non-contact data reception/transmission unit with such a structure, the following are given (for example, refer to patent document 5).
For example, a method of obtaining a disk-like non-contact data reception/transmission unit has been given in which a raw sheet and a cover sheet of the same material are bonded together with thermocompression bonding or a resin adhesive and the like so as to provide an inlet on the raw sheet and cover the inlet on this raw sheet, after which the layered product including the raw sheet, inlet and cover sheet is stamped into a circle in the laminating direction, with the inlet embedded in resin (hereinafter referred to as “the first method” in order to simplify the explanation).
Also, a method of obtaining a non-contact data reception/transmission unit formed to a predetermined shape with a metal die has been given in which an inlet is inserted in a metal mold for injection molding, after which melted thermoplastic resin is made to flow thereinto or a thermosetting resin is made to flow thereinto and heated, thereby embedding the inlet in the resin (hereinafter referred to as “the second method” in order to simplify the explanation).
Incidentally, in the first method, since a minimum thickness is required to be able to withstand the tension and pressure when the raw sheet is stamped into a disk, there is the problem that it is difficult to make the non-contact data reception/transmission unit smaller in thickness. In addition, since there is no portion that absorbs the thickness of the IC chip in the raw sheet and the cover sheet, there is the problem of increased pressure load on the IC chip. Moreover, since the adhesion of the raw sheet and the cover sheet is poor, as a result of forming by stamping, the joining end faces of both end up being exposed, and so when external pressure is applied, the raw sheet and the cover sheet may peel apart, exposing the inlet.
Furthermore, water and chemicals can easily seep inside from the joining end face of the raw sheet and the cover sheet, so that non-contact data reception/transmission units manufactured by this method have inferior water resistance and chemical resistance.
Moreover, in the second method, excessive pressure is applied to the inlet at the time of injection molding, and so there is the risk of damaging the IC chip or the antenna. Also, when the thickness of the base substrate is made thin in order to make a thin non-contact data reception/transmission unit in this method, at the juncture when resin is made to flow into the metal mold, cracking occurs in the base substrate due to the pressure of the resin, and so it is difficult to be made smaller in thickness.    [Patent Document 1] Japanese Unexamined Patent Application No. 2003-317052    [Patent Document 2] Japanese Unexamined Patent Application No. 2003-108966    [Patent Document 3] Japanese Unexamined Patent Application No. 2003-68775    [Patent Document 4] Japanese Unexamined Patent Application No. 2002-298116    [Patent Document 5] Japanese Unexamined Patent Application No. 2003-331243    [Non-patent Document I] TERAURA, Nobuyuki. “Development and Application of RF Tags: The Future of Wireless IC Chips”, 1st ed., CMC Publishing, 28 Feb. 2003, p 121, FIG. 2.